1. Field of the Invention
This invention pertains to an automatic toning apparatus of the type having a reciprocating hopper and, in particular, to a mounting arrangement for the reciprocating hopper.
2. Description of the Prior Art
Apparatus which automatically dispenses particulate toner material onto the imagewise tacky surface of a photo-element is known. Exemplary of such apparatus is that disclosed in U.S. Pat. No. 4,069,791 (Tobias), assigned to the assignee of the present invention. In the Tobias patent an exposed photo-element having an image-wise tacky surface thereon is conveyed in a predetermined direction beneath a hopper having particulate toning material therein. The toner is dispensed from the hopper as the photo-element is transported therebeneath. One wall of the hopper is fixed while the other wall thereof is reciprocated in a direction transversely to the movement of the photo-element. The transverse reciprocation of the one wall of the hopper causes particulate toner to fall from the hopper onto the surface of the photo-element. The reciprocating wall of the hopper also carries a brush pad which moves therewith. The transverse reciprocating movement of the pad embeds particulate toner dispensed from the hopper into the surface of the photo-element passing therebeneath.
Presently such a toning apparatus is driven by a barrel cam assembly and utilizes a dove-tail linear bearing arrangement which facilitates the transfer of reciprocating lateral oscillatory energy to the one wall of the hopper. Use of a linear bearing presupposes close operating tolerances which, as in the case of any mutually abrading surfaces, have a tendency to change as the bearing wears. Since the reciprocating wall of the hopper is mounted to one element of the bearing, wear in the bearing has the tendency of altering the clearance distance by which the hopper is spaced above the path of transport of the photo-element. A barrel cam by its nature generates vibratory forces and, as such, may be objectionably noisy in some environments. Such forces also tend to increase as the cam wears, thus necessitating a rather massive frame in order to absorb the vibratory energy. Further, a barrel cam has built-in backlash which increases as it is used. As a result of the use of both a dove-tailed bearing and a barrel cam drive, the vibratory frequency at which the hopper oscillates is limited.
In view of the foregoing it is believed advantageous to provide a mounting arrangement for the hopper of an automatic toning apparatus which eliminates the use of close tolerance linear bearings and thereby eliminates the possibility of bearing wear and of the alteration of the clearance space between the toning pad and the surface of the photo-element. Elimination of the close tolerances would provide, as an attendant advantage, ease of manufacture, assembly and maintenance. It is also believed to be advantageous to provide a mounting arrangement for the hopper which minimizes friction and wear and reduces weight, thereby minimizing noise. Further, it is believed advantageous to provide a drive arrangement for the hopper which avoids the backlash and vibration attendant with the use of the barrel cam drive mechanism. As a corollary, since vibration is minimized, the weight and size requirements of the frame is also commensurately lessened. Still further, constraints on hopper vibratory frequency are also reduced.